(AP Photo/Aaron Favila). United States' siblings Matt and Becca Hamilton huddle to discuss their strategy during their mixed doubles curling match against Switzerland at the 2018 Winter Olympics in Gangneung, South Korea, Friday, Feb. 9, 2018.

By KRISTEN GELINEAUAssociated Press

GANGNEUNG, South Korea (AP) - In a sport known for its politeness, the sight of American curlers Matt and Becca Hamilton banging their brooms against the Olympic ice in frustration was a bit of a rarity. But then so was the manner in which they lost the game.

Despite holding a 4-3 lead heading into the final end, or round, of curling's mixed doubles match Friday, the United States lost 9-4 to reigning world champion Switzerland after the Swiss managed something exceedingly unusual in curling: a perfect score known as a six-ender. How rare is a six-ender? Think of a perfect game in baseball.

First, a bit of a primer: Mixed doubles curling, which is making its Olympic debut in Pyeongchang, has different rules to standard curling. There are only two players on each team - a man and a woman - as opposed to four. There are eight ends instead of 10. And each team throws six rocks in each end instead of eight.

Although Switzerland was behind by one point going into the final end, Jenny Perret and Martin Rios had an advantage known as the hammer - the right to throw the final stone of the game. They managed to get their first five stones into the house, putting the Americans in a precarious position.

Becca Hamilton threw her final rock, which needed to get to the button - the center of the bull's eye-shaped target - in order to preserve their lead. "Hard, hurry, hurry!" she screamed at her brother, Matt, who was frantically sweeping the ice in a bid to get the stone to the right spot. "You got to go, go, go, go, go!!" She then raced ahead and joined in the sweeping frenzy as the rock drew close to the button.

It was not to be. The stone ended up a few inches past its target, prompting the disappointed siblings to slam their brooms against the ice. Switzerland promptly knocked the Americans' lone rock out of the house and kept all six of their stones within the target's rings, giving them that rare and coveted six-ender. (In regular curling, which uses eight stones, a perfect score is known as an eight-ender or "a snowman.")

No curling team has ever managed a perfect score at the Olympics, according to the World Curling Federation. Perfect scores in professional-level curling are so unusual that various countries' curling clubs have special awards for them. Curling Canada hands out pins and certificates to teams who score eight-enders. The American Curling Foundation & Museum has an eight-ender patch it bestows upon teams who nab perfect scores.

Rios laughed when asked if he was aware he and his teammate had set a record for first perfect curling score at the games.

"We wanted to win the game and that's it," he said. "I was making jokes about it during the last end, but just our focus was to score a deuce - that's it."

Despite the rough loss, the Hamiltons were gracious in defeat.

"They're a good team," Matt Hamilton said after the game. "They're defending world champs, so hats off to them. They made more shots."

The Hamiltons had another tough game during the afternoon round robin, conceding in the sixth end to South Korea after falling behind 9-1.

Afterward, Becca Hamilton said they were struggling to get used to the condition of the ice. In curling, the ice is covered in frozen water droplets known as "pebbles," and changes in the temperature or humidity can affect how the stone travels across the surface.

"We were throwing things heavy," Becca Hamilton said. "The ice was a little quicker and a little straighter and we didn't connect with it right away like Korea did."

Norway handed Switzerland its first loss during the afternoon session, beating them 6-5. In other mixed doubles action, Canada and Russian athletes each picked up two wins on Friday against Finland and China.

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